Flexible Flashing Material And Method of Manufacture

ABSTRACT

A flashing material for a building structure is provided. The flashing material includes a flexible water-resistive membrane having an upper textured surface with a series of separate, laterally paced-apart, elongate spacers bonded thereto. The elongate spacers can be polymeric filaments that define an air space and drainage paths across the upper surface of the membrane. Preferably, the filaments have a series of depressions formed therein that provide transverse drainage paths across the filaments. Sill, decking and other building structure assemblies and methods of making the flashing material are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 USC §119(e) of U.S.Provisional Patent Application No. 61/120,503, filed Dec. 8, 2008.

BACKGROUND OF THE INVENTION

The present invention relates to waterproofing a building structure,such as a building opening, a deck ledger or joist, a corner of anexterior wall, a roof-to-wall interface, a through-wall passage, or thelike, and more particularly, the present invention relates to a flexibledrainage-promoting flashing material and its method of manufacture.

By way of example, water leakage or seepage can occur through the jointsof a window and/or window frame, and moisture infiltration within andaround a window opening in a wall can be caused by blowing rain, meltingsnow or ice, and/or condensation of moisture vapor. Similar leakageand/or seepage can also occur via through-wall passages and otherbuilding openings, behind deck ledger boards, within a corner of anexterior wall or wall-to-roof interface, or at other areas of a buildingstructure. Moisture that infiltrates these areas will likely becometrapped within the building structure and over time will causestructural damage such as rotting of windowsills, framing elements,ledgers and joists, adjacent wall or roof sheathing and studs, andexterior sidewall and trim building materials. In addition, trappedmoisture will also cause the undesired growth of mold within the wall oradjacent structure.

For purposes of preventing such damage with respect to window openings,it is conventional practice to install a sill pan or like flashingmaterial to a window opening before a window is installed within theopening. The sill pan or like flashing material provides a waterimpermeable layer of material that prevents any moisture, which mayinfiltrate the opening, from contacting the generally wooden frameworkmembers of the sill and like surfaces within the wall. Preferably, thesill pan or flashing material should also permit and/or promote removalof moisture from the sill area to an area on an exterior side of thebuilding envelope. Thus, the sill pan and flashing is used to preventstructural damage of the building structure about the window opening,drain moisture to an exterior of the building, and lessen the likelihoodof mold forming within the walls of the structure.

By way of example, the following U.S. patents and U.S. publishedapplications disclose various known sill pans, sill drainage systems,flashing, and like building materials: U.S. Application Publication Nos.2008/0105363 A1 of Ford, 2008/0010917 A1 of Hopkins et al., 2006/0101726A1 of Collins, 2005/0217189 A1 of Moffit, 2008/0178557 A1 of Parsons etal., 2006/0010788 A1 of Nettleton, 2007/0289226 A1 of Lokkart,2006/0236618 A1 of Williams, 2006/0137263 A1 of Casey, 2003/0056444 A1of Ackerman, Jr., 2003/0177727 A1 of Gatherum, 2006/0143994 A1 of Allen,2007/0157528 A1 of Gawoski and 2005/0144856 A1 of Conlin and U.S. Pat.No. 6,676,779 B2 issued to Hopkins et al., U.S. Pat. No. 7,201,820 B2issued to Wiercinski, U.S. Pat. No. 6,964,136 B2 issued to Collins etal., U.S. Pat. No. 1,677,130 issued to Cherry, U.S. Pat. No. 4,555,882issued to Moffit et al., U.S. Pat. No. 7,222,462 B2 issued to Ellingson,U.S. Pat. No. 6,385,925 B1 issued to Wark, U.S. Pat. Nos. 5,822,933 and5,921,038 issued to Burroughs et al., U.S. Pat. No. 7,367,164 B2 issuedto Burton et al., U.S. Pat. No. 7,134,245 B2 issued to Burton, U.S. Pat.Nos. 6,401,402 and 6,401,401 issued to Williams, U.S. Pat. No. 6,725,610B2 issued to Murphy et al, U.S. Pat. No. 6,305,130 B1 issued toAckerman, Jr., and U.S. Pat. Nos. 7,059,087 B2 and 7,290,379 B2 issuedto Allen.

Although the sill pans, flashing materials, assemblies, and methodsdisclosed in the above referenced patents and published applications maybe satisfactory for their intended purpose, there is a need for animproved building material and method for waterproofing internalcomponents of a through-wall opening or the like of a structure, wallcorners, wall-to-roof interface areas, deck ledgers and joists and likestructures and for removing moisture that penetrates into such openingsor structures. The building material should be inexpensive tomanufacture and require only a minimum of skill and labor to applywithin an opening or on a structure.

SUMMARY OF THE INVENTION

A flashing material for a building structure is provided. The flashingmaterial includes a water-resistive membrane sufficiently flexible toconform to underlying surfaces and a series of separate, laterallyspaced-apart, elongate spacers bonded to an upper surface of themembrane. The elongate spacers are polymeric filaments and define an airspace and drainage paths across the upper surface of the membrane.

The filaments are of a thickness that projects to a predetermined heightabove the upper surface of the membrane and that defines a thickness ofthe air space above the upper face of the membrane. The filaments have aseries of depressions formed therein that do not extend to thepredetermined height and that provide drainage paths in a directiontransversely across the filaments, According to one contemplatedembodiment of the present invention, the series of depressions arelocated at spaced intervals along a length of each filament and areformed by flattened sections of the filaments, and each filament iscontinuous and consists of an alternating array of the flattenedsections and non-flattened full-size sections of the filament.

The membrane can be of multi-layer construction including an upper layerof polymeric material to which the filaments are bonded and a lowerintegral layer of adhesive providing an underside of the membrane. Arelease sheet can be used to cover the adhesive whereby the layer ofadhesive can be exposed when the release sheet is removed from themembrane. Alternatively, the membrane can be provided without anadhesive layer and release sheet. In addition, an elongate flexiblewedge can be secured to a rear edge portion of the underside of themembrane to provide the membrane with a forward slope from its rear edgetoward its front edge. Alternatively, the membrane can be providedwithout the integral wedge component.

According to another aspect of the present invention, an assembly of awindow, door, or like opening of a building is provided. The assemblyincludes framework defining an opening in an exterior wall of abuilding. The framework includes a sill member extending betweenopposite upright framing members. The assembly also includes an outersheathing member applied to the wall below the opening. A flexiblewater-resistive membrane is applied over the sill member and is foldedover a front edge of the opening and extends on the outer sheathingmember. The membrane has a series of separate, laterally spaced-apart,elongate spacers bonded to an upper surface of the membrane, and theelongate spacers are polymeric filaments that define an air space anddrainage paths across the upper surface of the membrane. Each of thefilaments extends generally in a direction from one of the uprightframing members to the opposite one of the upright framing members alongthe length of the sill member of the opening.

As discussed above, the filaments are of a thickness that projects to apredetermined height above the upper surface of the membrane and thatdefines a thickness of the air space above the upper face of themembrane, and the filaments have a series of depressions formed thereinthat do not extend to the predetermined height. The depressions providethe drainage paths which extend transversely across the filaments.Preferably, the series of depressions are located at spaced intervalsalong a length of each filament and are formed by flattened sections ofthe filaments, and each filament is continuous and consists of analternating array of the flattened sections and non-flattened full-sizesections of the filament.

The assembly can include a pre-applied layer of adhesive on theunderside of the membrane to adhesively secure the membrane to the sillmember and outer sheathing, and/or the assembly can include an elongatewedge or backdam secured to the sill member underneath a rear edgeportion of the membrane to provide the membrane with a forward slopefrom its rear edge toward its front edge. In addition, the assembly caninclude a window or the like installed within the opening over the sillmember and membrane. In this case, the air space and drainage paths areprovided between the upper face of the membrane and lowermost framingelements of the window, including a lower window flange of a flangedwindow. In addition, the same membrane with filament spacers used on thesill can also be applied adjacent the jambs and header of the openingbehind exterior window trim to promote drainage behind the trim.

A further aspect of the present invention is directed to a method ofmaking a flashing material for an opening in an exterior wall of abuilding. A series of separate, laterally spaced-apart, elongatepolymeric filaments are bonded on an upper surface of a flexiblewater-resistive membrane. The filaments are flattened at spacedintervals along their length to create drainage paths extendingtransversely across the filaments. The method can also include the stepsof applying a layer of adhesive on an underside of the membrane andthereafter applying a release sheet to the underside of the membrane tocover the layer of adhesive. Further, the method can include the step ofsecuring a wedge of flexible material to an underside of the membranealong a rear edge portion of the membrane.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a an exterior wall of a buildinghaving a window;

FIG. 2 is a partially cut-away perspective view of a flexible windowsill flashing material according to the present invention;

FIG. 3 is a cross-sectional of the flexible flashing material along line3-3 of FIG. 2;

FIG. 4 is a perspective view of the flexible window sill flashingmaterial of FIG. 2 applied to a window opening;

FIG. 5 is a cross-sectional view of a window opening and the flexiblesill flashing material installed within the window opening;

FIG. 6 is a perspective view of a wall on which the window and theflexible sill flashing material are installed before exterior trim andsidewall building materials are installed;

FIG. 7 is an elevational view of a wall on which the window flanges atthe header and jambs have been covered with the flashing materialaccording to the present invention; and

FIG. 8 is a perspective view of a deck ledger and joists on which aflexible flashing material according to the present invention isapplied.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a flexible membrane that can beused, for instance, to waterproof a sill surface of framework of awindow opening of a building structure. However, the flexible membraneis not limited to use in window openings and can also be used to promotedrainage at other locations within or adjacent an exterior wall and/orroof assembly of a building. Examples include use of the flexiblemembranes about building openings such as doors or the like, otherthrough-wall openings such as for conduits, pipes, wires and the like,wall corner and wall-to-roof interfaces, and deck ledger boards andjoists.

By way of example, the flexible membrane is applied to the windowopening at the sill before the window is installed. After installationof the window and adjacent outer sidewall and trim building materials,the membrane is embedded within the structure and hidden from sight. Theflexible membrane can also be utilized to promote drainage behind trimelements of an opening adjacent header and jamb surfaces and to protectthe sill surfaces of doors. Of course, the flexible membrane can also beused to promote drainage within a wall corner or wall-to-roof interfaceand about deck ledger boards and joists as discussed above.

According to one example, FIG. 1 illustrates a finished exterior wall 10of a building having a window 12, exterior window trim 70, and exteriorsiding material 74. Over the course of the life of the wall 10 andwindow 12, moisture may infiltrate through the joints of the window orits frame as well as through small cracks or the like between the wall10 and window 12 due to blowing rain, melting snow and ice, condensationof moisture vapor, and the like. Moisture often collects within the sillarea 14 of the wall beneath the window 12. Accordingly, it is importantto provide protection against moisture infiltration in the sill area 14and to provide a drainage path for any moisture accumulating in the sillarea 14 such that the moisture is properly directed to ambientatmosphere on an exterior side of the building envelope.

FIGS. 2 and 3 illustrate one contemplated embodiment of a membrane 20.The membrane 20 has waterproofing qualities and provides a substantiallyimpermeable barrier to moisture. As an example, the membrane 20 can bemade of a single sheet or multiple layered sheets of plastic, polymericmaterial, elastomeric material, rubber, synthetic rubber,bitumen-containing material, or any other water-resistive barriermaterial that is flexible and is of a size to cover the sill area of awindow opening as discussed below in greater detail.

The membrane 20 can be at least slightly elastic so that it can betightly fitted within and/or around corners of the window opening andcan accommodate various-shaped underlying surfaces, edges, overhangs,uneven surfaces, and the like. Alternatively, the membrane 20 need onlybe flexible and not elastic. Preferably, the membrane 20 is sufficientlytear-resistant such that it does not tear during installation of thewindow or over the expected life of the window installation. If desired,additional tear-resistance can be provided by using a multilayermembrane that includes one or more reinforcing layers, such as a meshreinforcing layer.

When the membrane 20 is applied to a window opening, it will typicallybe applied over a sloped sill area with a backdam or the like thatprevents undesired flow of moisture on the sill toward the inside of thebuilding. In some contemplated embodiments of the present invention, awedge 22 of material is pre-applied, adhered, bonded, or otherwisesecured to a rear portion 24 of the underside 26 of the membrane 20. SeeFIG. 2. Alternatively, the wedge 22 or some other type of backdam can beapplied separately to the window opening, and the membrane 20 canthereafter be applied over the wedge or backdam at the building site.

The embodiment of FIG. 2 integrates the wedge 22, or backdam, directlyon the membrane 20 and, as illustrated, the wedge 22 provides aforward-directed slope between its front and rear edges to provide aforward-sloped surface along the width of the wedge material 22. Thus,the wedge 22 elevates the rear portion 24 of the membrane 20 when themembrane 20 is applied to a substantially horizontally-disposed sillsurface. Accordingly, any moisture collected on an upper surface 28 ofthe membrane 20 will be directed by the force of gravity toward and offthe front edge of the sill and onto a water-resistive barrier (notshown) applied on and covering the wall sheathing adjacent the windowopening.

The wedge 22 can be made of any material having sufficient structuralrigidity to maintain the rear portion 24 of the membrane 20 elevatedwhen a structure (e.g., door or window) is installed on top of themembrane 20. Such material may include, without limitation, plastics,closed cell foams, and open celled foams. Another contemplated materialis an openwork mat of polymeric filaments. It is desirable that thewedge 22 be formed of a flexible material such that the resultingmembrane 20 is flexible for purposes of ease of installation.

In some contemplated embodiments of the present invention, the membranecan be formed of multiple layers. The upper surface 28 can be formed bya waterproof non-woven sheet layer such as known for use with respect tohousewrap materials. The underside 26 of the membrane 20 can be providedby a separate waterproof adhesive layer that bonds to the upper layerand that is used to bond the membrane 20 directly to the surface of theunderlying sill to which the membrane is applied. The adhesive layereliminates the need for nails, staples or like fasteners to pierce themembrane 20 or the use of a separately applied layer of adhesive orsealant. As an alternative, the membrane can be provided without anadhesive layer and can be secured to the sill with fasteners, tape,adhesives, or the like.

The membrane 20 illustrated in FIGS. 2 and 3 includes an adhesive layer,and therefore, also includes a release sheet 30 that is removably bondedto the adhesive underside 26 of the membrane 20. Thus, the membrane 20can be a peel-and-stick type of product. Removal of the release sheet 30exposes the adhesive nature of the underside 26 of the membrane 20 andpermits the membrane 20 to be adhered to a desired surface enablingready installation. As examples, the flexible release sheet 30 can bemade of foils, metals, plastics, or papers treated with silicon or othersubstances to provide a low level of adhesion to the underlying adhesivelayer 26 of the membrane 20. In addition, the single or multi-layermembrane 20, optional wedge material 22, and release sheet 30 all shouldbe capable of being readily cut thereby enabling the membrane to be cutto size to fit window openings of any dimension. Alternatively, themembrane 20 can be provided in various standard sizes of window openingsto avoid a cutting step.

The upper surface 28 of the flexible membrane 20 according to thepresent invention carries a series of spacing elements 32 that ensurethe presence of a small air space between the upper surface 28 of themembrane 20 and any other materials, such as the window frame or thelike, applied over the membrane 20. The spacing elements 32 also providedrainage paths on the upper surface 28 enabling moisture to drainforward on the membrane 20 and over the front edge of the sill areathereby preventing moisture from accumulating long term in the sillarea.

As best illustrated in FIGS. 2 and 3, the spacer elements 32 on theupper surface 28 of the membrane 20 are provided as a series ofseparate, laterally spaced-apart, elongate spacer elements that arcbonded, adhered, or otherwise integrally secured to the upper surface28. Preferably, the elongate spacer elements 32 are thermally bonded tothe membrane 20 at spaced intervals; alternatively, the elements 32 canbe thermally bonded to the membrane 20 continuously along their fulllength.

According to one contemplated embodiment of the present invention, thespacer elements 32 are filaments 34, such as continuous extrudedpolymeric filaments. Each filament 34 is bonded to the upper surface 28of the membrane 12 where it contacts the membrane 20 and extends in agenerally longitudinal direction generally following the direction ofthe front and rear edges, 36 and 38, of the membrane. Thus, when themembrane 20 is installed within a window opening, the filaments 34extend generally along the longitudinal axis and front and rear edges ofthe windowsill and the longitudinal axis of the backdam or wedge 22. Asan example, see FIG. 4.

In the illustrated embodiment, the filaments 34 are laterally anduniformly spaced-apart, do not intersect, and generally extend in awavy, undulating, serpentine or sinuous pattern. However, they can alsoextend substantially parallel to each other following a straighter path.Alternatively, the filaments 34 of the present invention can extend innon-linear, saw tooth, and/or random paths or the like and can intersectand/or cross at random locations or at uniform spaced intervals.

As best illustrated in FIG. 5, each filament 34 can have a substantiallycircular cross-section of a predetermined diameter “D”. Of course, othercross-sectional shapes can be utilized, such as square, rectangular,oval and triangular filament cross-sections. Accordingly, each filament34 projects a distance “D” from the upper surface 28 of the membrane 20to provide a desired spacing between an overlying building material andthe upper face 28 of the membrane 20.

Drainage paths “P” are provided transversely across the series offilaments 34. Preferably, this is provided by a series of depressions 40that are formed in the filaments 34. The depressions 40 can be createdby flattening the filaments 34 at spaced-apart intervals along thelength of the filaments 34. This is best illustrated in FIG. 3. Thus,each filament 34 includes an alternating array of depressions 40 andfull size filament sections 42. The flattened sections of the filaments34 forming the depressions 40 project a distance from the upper surface28 of the membrane 20 less than that of the diameter “D” of the fullsize filament sections 42. This permits the drainage of moisture and/orthe flow of air transversely across the filaments 34. Preferably, thedepressions 40 in adjacent filaments 34 are aligned to providesubstantially straight drainage/ventilation paths “P” that extendtransversely, or perpendicularly, across the filaments 34 and uppersurface 28 of the membrane 20. See path “P” shown in FIGS. 2 and 4.

The filaments 34 are preferably made of polymeric materials capable ofbeing extruded directly onto the upper surface 28 of the membrane 20 ora surface of a conveyer, drum, or like transfer mechanism. As examples,the filaments 34 can be made of nylon, polypropylene, polyester,polyolefin, polyethylene, or like material. By way of example, and notby way of limitation, each filament 34 can be extruded such that it hasa diameter “D” between about 1/64 to ¼ inch, can be flattened inintervals “I” of about 0.5 to 6 inches, and can be spaced a distance “S”of about ⅛ to 1 inch from adjacent filaments. Of course, otherdimensions, shapes, patterns, etc. can also be utilized.

Preferably, the filaments 34 are thermally bonded to the membrane 20.The polymeric material of the filaments 34 and membrane 20 engage, meltand then solidify together to fuse the filaments 34 to the membrane 20via the application of heat and/or pressure, particularly at thedepressions 40. Thus, a separately applied adhesive is not required, anda strong bond can be formed. The depressed sections 40 of the filaments34 that are flattened are particularly strongly fused to the membrane 20since the pressure exerted on the filaments 34 to create the depressions40 results in the formation of a strong bond between the filaments 34and membrane 20. Alternatively, adhesive bonding, sonic bonding,mechanical bonding, or other techniques can be utilized depending on thematerials of the filaments and membrane. Further, the upper surface 28of the membrane 20 can be textured to strengthen the bond, for example,see the grid like textured areas “T” randomly shown in FIGS. 2 and 4.

FIGS. 4 and 5 illustrate assemblies within which the flexible membrane20 is utilized to waterproof a sill surface 50 of the framework of awindow opening 52 while providing an elevated backdam 22. FIG. 4 showsthe membrane 20 applied to the sill surface 50 of the framework prior tothe installation of the window 54. Opposite ends, 56 and 58, of themembrane 20 extend partially up the upright studs 60 and 62 of theframework on opposite sides of the window opening 52 and tightly conformto the corners of the window opening 52. As an alternative, the oppositeends, 56 and 58, of the membrane 20 can be applied only over thewindowsill itself and not onto the upright studs 60 and 62. In thiscase, other waterproofing materials would first he installed in thecorners of the window opening, and thereafter, the membrane 20 would beinstalled on the windowsill.

If required, the wedge 22 can be cut away and removed from the oppositeend sections, 56 and 58, of the membrane 20 that are adhered and/orsecured to the studs 60 and 62. The remainder of the membrane 20 andwedge 22 extends on the horizontally-disposed sill member 64 and can bebonded thereto after the release sheet 30 is removed from the undersideof the membrane 20 in a peel-and-stick manner. The wedge 22 extendsunder the rear portion 24 of the membrane 20 and can also be bonded orotherwise secured to the sill member 64 such that the wedge 22 forms abackdam along a rearward edge of the windowsill. The forward portion 66of the membrane 20 is folded over the front edge of the windowsill 64and adhered or secured to the outside surface of the vertically-disposedsheathing 68.

As best illustrated in FIG. 4, each elongate filaments 34 is continuousand extends in a direction generally from upright stud 60 to uprightstud 62 and in a relatively longitudinal direction on the sill member64. The depressions 40 permit moisture to flow along drainage paths “P”transversely across the filaments 34 from the rear portion 24 of themembrane 20 toward and off the front edge of the windowsill 64. See FIG.4.

A window 54, door, or the like may be placed on the membrane 20 and sill64 and installed within the opening 52. The wedge 22 forms a backdam orelevated area along the rearward edge of the windowsill 64. The forwardedge portion 66 of the membrane 20 extends over the outside surface ofthe sheathing 68 and will be at an elevation lower than that of the rearportion 24 of the membrane 20 disposed over the wedge 22. Accordingly,the downward slope provides a flow path “P” across the depressions 40 ofthe filaments 34 and away from the rear of the sill 64 such thatmoisture is directed forwardly off the windowsill 64 underneath thewindow 54. See FIG. 5.

The above described flexible membrane 20 having the filament spacers 34can also be used at other locations within the assembly fordrainage-promoting purposes, such as behind exterior window trim 70 (seeFIG. 1). For example, after the window 54 is installed within theopening 52, the membrane 20 can be applied over the flanges 72 of thewindow 54 adjacent the jambs and header of the window 54. See FIGS. 6and 7. If needed, the membrane 20 is cut to a desired size for thisapplication. After the membrane 20 is installed over the flanges 72, theexterior window trim 70 or like exterior siding material is applied overthe membrane 20.

The filaments 34 provide drainage paths on the upper surface 28 of themembrane 20 underneath the trim 70. This is true regardless of theorientation of the filaments 34 on the membrane 20. For instance,drainage paths are provided between adjacent, spaced-apart filaments 34as well as transversely across the filaments 34 via the depressions 40.

As stated above, the flexible membrane flashing material can be appliedto other building openings, such as doors, skylights, and the like, aswell as to through-wall openings for wires, cables, pipes or otherconduits. The membrane can also be applied within and along wall cornersand within and along wall-to-roof interfaces which form cornerstructures or the like.

Further, as illustrated in FIG. 8, the membrane 20 according to thepresent invention can be applied over a deck ledger board 80 of a deck.The deck ledger board 80 is fastened to a wall structure 82 of abuilding, and the membrane 20 is positioned to prevent water andmoisture from seeping behind the ledger board 80 to a location betweenthe ledger board 80 and the adjacent wall 82. The filaments 34 on theexterior face 28 of the membrane 20 provide spacing elements and theflattened sections 40 of the filaments 34 provide drainage paths “P”transversely across the filaments 34. Thus, any moisture penetratingwithin this area will be directed down and over the ledger board 80 bythe membrane 20. The membrane 20 can also be applied over the upperedges 84 of the deck joists 86 so that any moisture penetrating betweenthe joist 84 and upper deck members (not shown) can drain or be removedby evaporation from the upper edges 84 of the joists 86 to prevent waterdamage to the joists 86 and/or the overlying deck members.

While preferred flexible membranes, assemblies, and methods have beendescribed in detail, various modifications, alterations, and changes maybe made without departing from the spirit and scope of the presentinvention as defined in the appended claims.

1. A flashing material for a building structure, comprising: a flexiblewater-resistive membrane; and a series of separate, laterallyspaced-apart, elongate spacers bonded to an upper surface of saidmembrane, said elongate spacers being polymeric filaments and definingan air space and drainage paths across the upper surface of saidmembrane.
 2. A flashing material according to claim 1, wherein saidfilaments are of a thickness that projects to a predetermined heightabove said upper surface of said membrane and that defines a thicknessof said air space above said upper face of said membrane, and whereinsaid filaments have a series of depressions formed therein that do notextend to said predetermined height and that provide said drainage pathswhich extend transversely across said filaments.
 3. A flashing materialaccording to claim 2, wherein said series of depressions are located atspaced intervals along a length of each filament and are formed byflattened sections of said filaments, and wherein each filament iscontinuous and consists of an alternating array of said flattenedsections and non-flattened full-size sections of said filament.
 4. Aflashing material according to claim 3, wherein said filaments arethermally bonded to said membrane and do not intersect.
 5. A flashingmaterial according to claim 4, wherein said membrane has a multi-layerconstruction and includes an upper layer made of a sheet of polymericmaterial having a textured upper surface to which said filaments arebonded and a lower adhesive layer providing said membrane with aself-stick property.
 6. A flashing material according to claim 5,further comprising a release sheet covering said underside of saidadhesive layer whereby said adhesive layer is exposed when said releasesheet is removed from said membrane.
 7. A flashing material according toclaim 6, further comprising an elongate flexible wedge secured to a rearedge portion of said underside of said membrane to provide said membranewith a forward slope from its rear edge toward its front edge.
 8. Aflashing material according to claim 7, wherein said elongate wedge hasopposite ends defining opposite end sections of said membrane, andwherein said filaments extend in a direction substantially from one endsection of said membrane to said opposite end section of said membrane.9. A flashing material according to claim 8, wherein said wedge is madeof an openwork mat of polymeric filaments.
 10. An assembly of a buildingopening, comprising: framework defining an opening in an exterior wallof a building, said framework including a sill member extending betweenopposite upright framing members; one or more outer sheathing membersapplied to the wall surrounding said opening; and a flexiblewater-resistive membrane applied over said sill member and being foldedover a front edge of said opening onto said outer sheathing member, saidmembrane having a series of separate, laterally spaced-apart, elongatespacers bonded to an upper surface of said membrane, said elongatespacers being polymeric filaments and defining an air space and drainagepaths across said upper surface of said membrane; each of said filamentsextending generally in a direction from said one upright framing memberto said other upright framing member along the length of said sillmember of said opening.
 11. An assembly according to claim 10, whereinsaid filaments are of a thickness that projects to a predeterminedheight above said upper surface of said membrane and that defines athickness of said air space above said upper face of said membrane, andwherein said filaments have a series of depressions formed therein thatdo not extend to said predetermined height and that provide saiddrainage paths which extend transversely across said filaments.
 12. Anassembly according to claim 11, wherein said series of depressions arelocated at spaced intervals along a length of each filament and areformed by flattened sections of said filaments, herein each filament iscontinuous and consists of an alternating array of said flattenedsections and non-flattened full-size sections of said filament, andwherein said filaments do not intersect.
 13. An assembly according toclaim 12, wherein said membrane has a multi-layer construction andincludes an upper layer made of a sheet of polymeric material having atextured upper surface to which said filaments are thermally bonded anda lower adhesive layer providing said membrane with a self-stickproperty.
 14. An assembly according to claim 13, wherein said undersideof said membrane is adhesively secured to said sill member and saidouter sheathing by said adhesive layer.
 15. An assembly according toclaim 14, further comprising an elongate wedge or backdam secured tosaid sill member underneath a rear edge portion of said membrane toprovide said membrane with a forward slope from its rear edge toward itsfront edge.
 16. An assembly according to claim 15, further comprising awindow installed within said opening over said sill member and saidmembrane, and wherein said air space and said drainage paths areprovided between said membrane and a lowermost framing element of saidwindow.
 17. An assembly according to claim 16, further comprising: atleast one additional membrane identical to that applied over said sillmember that is applied over a window flange extending from said windowadjacent at least one of the jambs or header of the window; and anexterior window trim member applied over said at least one additionalmembrane.
 18. A method of assembling a window opening in a wall of abuilding, comprising: installing framework defining an opening in anexterior wall of a building, the framework including a sill memberextending between opposite upright framing members; applying outersheathing members to the wall about the opening; and securing a flexiblewater-resistive membrane over the sill member and folding a front edgeof the membrane onto the outer sheathing member extending below the sillmember, said membrane having a series of separate, laterallyspaced-apart, elongate spacers bonded to an upper surface of themembrane, the elongate spacers being polymeric filaments and defining anair space and drainage paths across the upper surface of the membrane,each of the filaments extending generally in a direction from the oneupright framing member to the other upright framing member along thelength of the sill member of the opening.
 19. A method according toclaim 18, further comprising a step of installing a flanged windowwithin the opening over the sill member and the membrane.
 20. A methodof making a flashing material for a sill of an opening in an exteriorwall of a building, comprising the steps of: bonding a series ofseparate, laterally spaced-apart, elongate polymeric filaments on anupper textured surface of a flexible water-resistive membrane; andflattening said filaments at spaced intervals to create drainage pathsextending transversely across said filaments.
 21. A method according toclaim 20, wherein said water-resistive membrane is made of a polymericmaterial, wherein, during said bonding step, said extruded polymericfilaments are thermally bonded to said membrane, and further comprisingthe step of applying a layer of adhesive on an underside of saidmembrane and thereafter applying a release sheet to the underside ofsaid membrane to cover said layer of adhesive.